GS850 acts weird when hot

[zblip2]

Hi,

Got a GS850G 1981 24,000 miles. It has performance quirks and I want to know if they are normal. First off, the bike idles fine, but it seems to have a dead spot in power at around 2 to 4 krpm, when accelerating. It is more obvious when the bike is cold but is still present at running temperatures, and shows up as a dip in power.

Another issues occures when the bike is realy hot:
It makes a mechanical clickclickclick rattle when accelerating from a stop. The clicking is in the 1 to 3 krpm zone. Plus, when starting from a stop at low speed, the engin seems unstable when letting go of the clutch.

Any Idea what these are about?

Thanks for your input.

[longgreensilverado]

here's 20 questions to answer your question:

are the carbs clean/and air filter
proper spark plugs?
petcock rebuilt or cleaned?
have the valves bee adjusted?
is the gas old?
check your plug wires and the plug caps that connect to the spark plugs
what shape are the boots in and out of the carbs, or do you have the individual air filters?

anyway it could be anyone of these and a or a combination

[zblip2]

here's 20 questions to answer your question:

are the carbs clean/and air filter
proper spark plugs?
petcock rebuilt or cleaned?
have the valves bee adjusted?
is the gas old?
check your plug wires and the plug caps that connect to the spark plugs
what shape are the boots in and out of the carbs, or do you have the individual air filters?

anyway it could be anyone of these and a or a combination

OK, so what you are telling me is that it is not a normal behavior for a GS850... I sort of thought these quirks where traits of caracter of an old bike. I really would like to try another GS850 only to see if it acts like mine...

As for your questions:
The carbs have not been cleaned since I bought the bike a year ago.
Spark plugs were installed by dealer last year
Never checked petcock
Valved ajusted this year.
Gas is new
Never checked the boots nor the air filter.

Guess I have work to do then.

Thanks for the input

[jimcor]

It is not normal.

Did YOU do the valves? If you had someone else do it chances are good you got a "wall job". (Park it over there, sir, by the wall....Yes sir, your bike is finished, it's parked right there by the wall.)

Buy some new plugs. Put 'em in. If you didn't do it could be no one did.

Buy and install new foam in the air cleaner. Oil the foam properly.

Start engine, spray boots at engine and at carb dead air box with water, or WD-40 checking for change in RPM, indicating air leak. Probably will need new O rings at engine/carb intake manifold boots.

Petcocks are a bitch. I flat out HATE vacuum operated petcocks. The worst "advance" ever made to a motorcycle's fuel system. Your problem doesn't sound like a petcock problem. Still check vacuum line for integrity and connections at petcock and carb rack. Try running bike with handle set on Prime. If it runs better, buy a new one. Don't bother with a rebuild kit, they don't work...do a search to corroborate that statement.

Good Luck. You're not far from having a good runing bike. Then again if you're willing to overlook a few glitches...you already have one.

[tomcat24551]

...Another issues occures when the bike is realy hot:
It makes a mechanical clickclickclick rattle when accelerating from a stop. The clicking is in the 1 to 3 krpm zone.

Plus, when starting from a stop at low speed, the engin seems unstable when letting go of the clutch.

Any Idea what these are about?

Regarding the "clickclickclick", is the noise constantly present at every rpm between 1000 and 3000 rpm or does it just show up at one or more certain places, like, say 1800 and/or 2200 and/or 2800 rpm, etc?

What do you mean that "the engin seems unstable when letting go of the clutch"? Can you be more specific? Do you mean that the clutch wants to chatter a little as it engages--or do you mean that its a little hard to keep the throttle and rpms just right when starting off from a stop?

Thanks

Tomcat

[zblip2]

Eureka!

I think I found the source of my problems

I was resigned to do a carb job, so I took off the tank and disconected the air box. And,then, while at it, I proceded to check the state of the air filter. Not knowing exactly how to do this, I unscrewed the wrong (left) side of the air box, giving me a reversed view of the air filter. While trying to figure out how to remove the filter, I noticed that one of the metal brackets designed for holding it tightly against the roof of the air box, was bent sideways. The air filter rim had slipped under the bracket and there was an 1/2 inch gap between the filter and the roof. The filter was brand new and clean cause evidently, it didn't filer air at all since the air was going through the gap instead of through the filter. I fixed that up, and, instead of going through with the carb job, I put the bike together and went for a test drive. Weirdly enough, all the quirks I was talking about, seem to have dissapered.(?!) Could a badly fitted air filter have a relation with the performance of a motorcycle? Does this make sense? Anyways, oddly enough, the power curve seems a lot more linear, the roll ons from a stop are ok now whatever the motor temperature, and I havent heard any clickclicks. Another thing, the sound of the motor seems to sound a bit less ''raspy'' on the highway.... Funniest thing is, had I unscrewed the right side of the airbox, I probably wouldn't have noticed the gap, and I would have searched endlessly for the cause of the quirks. There's a god for poor mechanics.

Seems I got myself a brand new bike!

Thank you all for your precious imput.

[bwringer]

Yes, a misplaced air filter or leaky airbox will have a profound negative effect on a GS850. The entire intake path must be airtight.